Muffler with internal side branch chamber



March 1950 J. R. FLUOR ETAL 2,501,767

MUFFLER wrm INTERNAL SIDE BRANCH CHAMBER Filed March 1, 1948 INVENTORS.zYH/v Rose-e1- fizz/0e,

Fosv-Ee M. STEPHENS,

AQNOLD BHRTELS, glmeL Es NEWMAN, Y

141- T'ORNE'Y.

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UNITED STATES PATENT OFFICE MUFFLER WITH INTERNAL SIDE BRANCH CHAMBERJohn Robert Fluor, Foster M. Stephens, Arnold Bartels, and CharlesNewman, Los Angeles, Calif., assignors to The Fluor Corporation, Ltd.,Los Angeles, Calif., a corporation of California Application March 1,1948, Serial No. 12,375

This invention has to do broadly with the elimination or dampening ofpulsations in gas streams, and is concerned particularly, thoughtypically, with the mufiiing of engine exhaust gas streams for theremoval of pulsations predominating in the audible frequency range.

In the illustrative embodiment hereinafter described. the invention hasadaptability to particular ad- .vantage for mufiiing the exhaust gasdischarge from stationary engines, e. as used in compressor plantinstallations.

One of our major objects is to effect more efficient mufiiing of audiblesound frequencies -by equipment characterized by its advantages fromstandpoints of production facility and substantially reduced cost incomparison with conventional apparatus of comparable efliciency,

In certain of its aspects the invention is directed to mufiiingequipment applicable to an engine in a building or room, and from whichthe exhaust gas is discharged to the outside, as within a stack shell.As adapted to such installations the invention contemplates a dualchamber arrangement in the nature of a pair of acoustical capacitancesrespectively inside and outside the engine room, and an elongated pipeinterconnecting the chamber for series flow of the gas therethrough, andhaving characteristics of an acoustical inductance.

of employing the vertical outside stack shell as a second capacitance.

A further important feature and object of the invention is the use inconjunction with an acoustical capacitance chamber, and specificallywith each of the chambers in the above mentioned dual chambers system,of a communicating closed space or chamber itself serving to cancel outgas stream pulsations by reason oiits individual characteristics as anacoustical filter. In this respect. the invention contemplates use 01 aclosed chamber having a restricted inlet communication with a secondarychamber, the gas surgin into and out of the --closed chamber through therestricted inlet, and

the chamber and inlet being so proportioned as to form an acousticalfilter having a resonant frequency corresponding substantially to thedominating pulsation The above mentioned as well as various additionalfeatures and objects of the invention will be understood to betteradvantage from the As will appear,. the invention incorporates thepractical feature frequency in the gas 9 Claims. (Cl. 181--59) followingdetailed description of an illustrative 2 embodiment shown generally insection by the accompanying drawing.

Referring to the drawing, an internal combustion engine,diagrammatically indicated at m, is shown to be contained in a room R,with the exhaust gas discharge conducted through the room wall H to thestack assembly l2 at the outside. Exhaust gases are discharged from theengine through a pipe Iii into a first chamber assembly generallyindicated at M, and thence through an elongated pipe iii to a secondchamber arrangement I6 in the stack assembly [2.

The exhaust pipe l3 communicates by way of a perforated tubular sectionI! with a closed chamber I8, the latter being closed in the sense thatexhaust gases can enter and leave the chamber only by surging flowthrough a restricted inlet. Preferably, such inlet is formed by aperforated plate I9, the total apertured area of which is such as torestrict the exhaust gas flow into chamber l8. This closed chamber,together with restricted inlet, constitutes essentially an acousticalfilter which may be designed, by proportioning the chamber volume andthe effective restriction to gas flow presented by the perforated platei 9, as to have a resonant frequency (i. e., frequency of gas surge intoand out of the chamber) corresponding substantially to the frequency ofthe dominating pulsations in the gas stream. Thus the effect of thechamber I8 is to accomplish an initial canceling out of pulsationeffects, particularly while functioning in conjunction with a secondchamber 2i! having restricted communication with the exhaust gas feedthrough the perforated tubular section l1.

Chamber 20 is formed by an outer shell 2| axially aligned with the innerchamber l8 and having an end closure 22 about the inlet l3. The forwardend of shell 2! is tapered at 23 to connect with the elongated pipe I 5.The latter in turn is connected at 24 with an enlarged pipe section 25having restricted communication through perforated plate 25 with chamber21, the structural and functional characteristics of which are similarto those previously described with reference to chamber l8. Pipe 25 hasrestricted communication through the perforated tubular section 28 withthe enlarged chamber 29 in the vertically extending stack shell 38, thelatter having a bottom closure 3! and a convergent upper end 32containing an outlet which may be formed by pipe 33 having a perforatedsection 34.

Where it may be desirable that the muffling assembly be air-cooled, orthe energy of the exhaust gas stream utilized to Withdraw air from theengine room R, provision may be made for inducing air flow from the roomby the exhaust gas discharge from the outlet 33. For this purpose, shell38 may be contained within and annularly spaced from the outer shell 35having a convergent head 36 and stack 31 forming a Venturi throat, theexhaust gas discharge into which from outlet 33 induces air flow throughthe inter-shell space 38. At this point it may be mentioned that becauseof the exceptionally high degree to which the mufiiing system acts toremove the exhaust gas stream pulsations, the air displacementefficiency, i. e., the ratio of induced air to exhaust gas, isexceptionally high. The air flow is induced from the engine room throughthe flared inlet 40 and conduit M annularly spaced about the pipe I5 andconnecting at '52 with the shell 35.

In the operation of the muilling system, gas stream pulsations initiallyare subjected to the nullifying or canceling eilect of the acousticalfilter system consisting of the chambers 18 and 2n and the restrictionspresented by the perforated elements H and 19. The exhaust gas streamthen passes through the extended in ductance pipe l5 wherein its flow isrestricted with relation. to chambers 20 and 25. Any remainingpulsations in the gas stream then be come subjected to canceling out bythe acoustical filter system presented by chambers 21 and 29,

and the gas passage restrictions presented by the perforated areas 26and 28.

We claim:

1. Apparatus for eliminating gas stream pulsations comprising an outershell having a gas out let, an inner shell extending longitudinallywithin and spaced from said outer shell and having a closed end towardsaid outlet, an inlet pipe connccted to said shells, and means forming aplurality of restrictions in the end of said inner chamber toward theinlet pipe and through which the inlet surges into and out of the innerchamber and flows into said outer chamber to the outlet.

2. Apparatus for eliminating gas stream pulsations comprising an outershell having a tapered end forming a gas outlet, an inner shellextending longitudinally within and spaced from said outer shell andhaving a closed end toward said outlet, an inlet pipe connected to saidshells, and means forming a plurality of restrictions in the end of saidinner chamber toward. the inlet pipe and through which the inlet gassurges into and W out of the inner chamber and flows intosaid outerchamber to the outlet.

3. Apparatus for eliminating gas stream pulsations comprising an outershell. having a gas outlet, an inner shell extending longitudinallywithin and spaced from said outer shell and having a closed end towardsaid outlet, an inlet pipe connected to said shells, and a perforatedplate forming the end of said inner chamber toward the inlet pipe andthrough which the inlet gas surges into and out of the inner chamber andflows into said outer chamber to the outlet.

4.. Apparatus. for eliminating gas stream pulsations comprising an outershell having a gas outlet, an inner shell extending longitudinallywithin and spaced from said outer shell and having a closed end towardsaid outlet, an inlet pipe connected to said shells, means forming aplurality of restrictions in the end of said inner chamber" toward theinlet pipe and through which the inlet gas surges into and out of theinner chamber and flows into said outer chamber to the outlet, and meansforming a plurality of restrictions at the inlet side of the firstmentioned restrictions and through which the gas passes in flowingoutwardly into said outer shell.

5. Apparatus for eliminating gas stream pulsations comprising an outershell having a gas outlet, an inner shell extending longitudinallywithin and spaced from said outer shell and having a. closed end towardsaid outlet, an inlet pipe connected to said shells, and means forming aplurality of restrictions in the end of said inner chamber toward theinlet pipe and through which the inlet gas surges into and out of theinner chamber and flows into said outer chamber to the outlet, saidinlet pipe being a perforated section through which the gas at the inletside of the first mentioned restrictions passes in flowing outward- 1yinto said outer shell.

6. Apparatus for eliminating gas stream pulsations, comprising a pair ofshell assemblies through which the gas flows in series, each of saidassemblies comprising an outer shell having a gas outlet, an inner shellextending longitudinally within and spaced from said outer shell andhaving a closed end toward said outlet, an inlet pipe connected to saidshells, means forming a plurality of restrictions in the end of saidinner chamber toward the inlet pipe and through which the inlet gassurges into and out of the inner chamber and flows into said outerchamber to the outlet, the inlet pipe connecting with the shells of thesecond shell assembly leading from the gas outlet of the outer shell ofthe first assembly.

7. Apparatus as claimed in claim 6, in which said inlet pipe connectingwith the shells of the second shell assembly is elongated and hasconsiderably smaller diameter than said outer shells.

8. Apparatus as claimed in claim 6, in which said inlet pipe connectingwith the shells of the second shell assembly has enlarging taperedconnections with the second shell assembly and with the gas outlet ofthe outer shell of the first assembly.

9. Apparatus as claimed in claim 6, in whic the outer shell of thesecond shell assembly is a vertically positioned stack located remotefrom the first shell assembly.

JOHN ROBERT FLUOR. FOSTER M. STEPHENS. ARNOLD BARTELS. CHARLES NEWMAN.

REFERENCES CITED The following references are of record in the file oithispatent:

UNITED STATES PATENTS

